JPH09161738A - Explosionproof grooving method for battery container and nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily provide a groove having a stable operation pressure with good reproducibility with no dispersion on the pressure strength of a machined section by applying explosionproof grooves on the outside bottom face of a battery container by laser beam machining. SOLUTION: A laser beam is selectively applied and scanned on the outside bottom face 1a of a metal battery container 1 to form an explosionproof groove 2. The thickness of the thin section 1b of the groove 2 is preferably set to about 0.02-0.08mm, and the shape is preferably set to the cross of straight lines, e.g. X-type, Y-type, or H-type on the plan view. Grooving is applied by laser machining, and such problems as the hardening caused by mechanical machining and the abrasion and damage of a press punch are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of grooving a battery container for preventing explosion and a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years, as non-aqueous electrolyte batteries, negative electrodes using light metals such as lithium, sodium and potassium as negative electrode active materials, positive electrodes using metal oxides, sulfides or halides as positive electrode active materials, and Batteries equipped with a water electrolyte as a power generating element have been attracting attention as batteries having high voltage, high energy density and long-term reliability (good storage characteristics and a wide operating temperature range). For example, lithium batteries that use manganese dioxide (MnO ₂ ), fluorocarbon (CF ₂ ) _n , thionyl chloride (SOCl ₂ ) as a positive electrode active material are often used as calculators, clock power supplies, and memory backup batteries. . That is, a non-aqueous electrolyte battery such as a lithium battery has a smaller self-discharge than a silver battery or an alkaline battery, and can withstand long-term use. Therefore, it is used as a power source for the calculator, the clock, and the like.

In this type of non-aqueous electrolyte battery, the battery power generating element is airtightly contained in a metal battery container such as stainless steel, and the electrolyte is, for example, propylene carbonate. , An ethylene carbonate, 1,2-dimethoxyethane, γ-butyrolactone, tetrahydrofuran, and other organic solvents in which a lithium salt such as LiCl0 ₄ , LiBF ₄ , LiAsF ₆ is dissolved to form an organic electrolyte (non-aqueous electrolyte) It is used. Further, a carbonaceous porous body is generally used as a support for the positive electrode active material, and an austenitic stainless steel having a nickel content of 3 to 20% by weight is generally used as a positive electrode current collector or a battery container.

In the case of the non-aqueous electrolyte battery, by adopting a hermetic structure using a glass seal and a complete hermetic structure by laser light sealing, it is possible to significantly reduce self-deterioration and improve long-term storability. It is characterized by the fact that it is used. However, the complete sealing of the structure, on the other hand, raises the following problems. That is, (a) a short circuit due to contact between lithium of the negative electrode inside the battery and the positive electrode current collector, (b) when the positive and negative electrodes of the battery were accidentally shorted externally, (c) the battery was thrown into a fire. When (d) the battery is heated to a high temperature, or (e) the battery is charged at a high voltage, or when exposed to a so-called abnormal environment, a rapid reaction occurs inside the battery, The internal pressure of the cylinder rises abnormally. Then, the abnormal increase in the internal pressure may cause the battery container to rupture or the hermetic part of the glass to be broken, and the electrolyte solution in the battery power generation element to be jetted and scattered.

For such an abnormal increase in the internal pressure of the battery, a V-shaped groove for preventing a violent explosion is formed in advance by press working on the outer bottom surface of the battery container.
When the internal pressure of the battery rises abnormally, a means has been developed to reduce the damage by breaking the V-shaped groove of the cross section and letting the internal pressure escape (for example, Japanese Utility Model Publication No. 58-17332).
JP-A-63-86244, etc.).

[0006]

However, when the V-shaped groove for preventing the explosion is formed in a sharp groove, not only is there a problem that the durability of the die used is impaired, The sharp groove is likely to be broken, so that undesired cracking of the battery container may be easily caused and the durability of the battery container may be impaired. Also, by pressing,
When a V-shaped groove with a cross-section for preventing explosion is formed, generally, the opposite surface side corresponding to the V-shaped groove is projected, but the rigidity of the formed groove is increased by press work hardening. To increase.

This increase in the rigidity of the groove increases the working pressure of the safety device and also increases the variation of the working pressure, and as a result, there is a problem that the safety device may not operate at the set working pressure. . Therefore, it is necessary to remove the work hardening by annealing after forming the V-shaped groove of the required cross section by the press working, which not only complicates the working process, but also increases the cost. There is an upper problem.

On the other hand, it is also known that a groove having a flat bottom surface for preventing an explosion is formed on the outer bottom surface by press working in which required molds are arranged on the outer and inner sides of the bottom surface of the battery container. (For example, JP-A-63-285860). That is, while the battery container is fitted and arranged in a cylindrical lower mold having an upper surface that conforms to the inner bottom surface shape of the battery container, a molding that also has a shape that conforms to the outer bottom surface shape of the battery container. Lower the die (upper die).
There is also known a means for maintaining a predetermined size by pressurizing the bottom surface of the battery container between both molds to flatten the bottom surface extruded by the formation of the burst explosion prevention groove. .

However, when a V-shaped groove having a cross section for preventing an explosion is formed by press working, the cross-sectional shape of the V-shaped groove formed varies depending on the shape of the tip of the punch for pressing. . In other words, in order to stably form the explosion-proof groove that functions as a highly reliable safety device, the press punch tip requires frequent daily management, and further work hardening is removed. The operation is complicated, for example, because an annealing process is required. These problems are serious when considering mass productivity, and development of effective solutions or processing techniques is desired.

The present invention has been made in view of such circumstances, and is a battery capable of stably forming a V-shaped groove having a V-shaped cross section for preventing an explosion explosion which functions as a highly reliable safety device. An object of the present invention is to provide a container processing method and a highly reliable non-aqueous electrolyte battery with a safety device.

[0011]

According to a first aspect of the present invention, there is provided a method of forming a groove for preventing explosion in an outer bottom surface of a metal battery container having a battery power generating element built therein, the groove forming being a laser beam. A groove forming method for preventing explosion of a battery container, which is characterized in that the groove is formed by processing.

A second aspect of the present invention is characterized in that, in the method of grooving a battery container for preventing explosions according to the first aspect, the metal battery container is made of stainless steel.

According to a third aspect of the present invention, a non-explosive explosion preventing groove is formed on the outer bottom surface of a metal battery container containing a negative electrode constituent member, a positive electrode constituent member, and a battery power generating element having a non-aqueous electrolyte solution. It is a water-electrolyte battery, wherein the explosion-proof groove is formed by laser light processing.

The invention of claim 4 is the non-aqueous electrolyte battery according to claim 3, characterized in that the metal battery container is made of stainless steel.

In the present invention, the thickness of the thin portion (thickness of the bottom wall surface of the groove) of the explosion-proof groove (safety device) formed by laser light processing on the outer bottom surface of the metal battery container is generally To
It is preferably about 0.02 to 0.08 mm, and it is desirable to form a straight cross-over / branch type such as an X-shaped, Y-shaped, H-shaped or * -shaped (radial type) in plan view. Here, the metal battery container generally has a nickel content of 3 to 20% by weight.
Of austenitic stainless steel, and its shape, dimensions, wall thickness, etc. are appropriately selected according to the capacity of the target battery.

In the non-aqueous electrolyte battery according to the present invention, examples of the positive electrode active material include active materials such as manganese dioxide, carbon fluoride and thionyl chloride. Further, examples of the negative electrode include metallic lithium foil and metallic sodium foil.

Examples of the non-aqueous electrolyte used in the non-aqueous electrolyte battery according to the present invention include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, acetonitrile, 1,2-dimethoxymethane, 1,3. -Dimethoxypropane,
An organic solvent (non-aqueous solvent) consisting of at least one selected from the group consisting of dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate is added to lithium perchlorate (LiClO ₄ ), hexafluoride. Lithium phosphate (LiPF ₆ ),
Lithium borofluoride (LiBF ₄ ), lithium arsenide hexafluoride (LiAsF ₆ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) and other lithium salts (electrolytes) 0.5 to
A non-aqueous electrolytic solution in which about 1.5 mol / l is dissolved is generally cited. Instead of the non-aqueous electrolyte solution, an ion conductive solid electrolyte, for example, a polymer solid electrolyte obtained by compounding a lithium salt with a polymer compound may be used.

Further, as the separator for insulating and separating the negative electrode and the positive electrode, for example, a nonwoven fabric of polyolefin resin such as polyethylene or polypropylene or a porous film may be used.

In the first and second aspects of the present invention, the groove for preventing the explosion is formed on the outer bottom surface of the metal battery container by laser light processing. Therefore, the work portion caused by work hardening and wear / damage of the press punch is processed. It is also possible to avoid variations in the pressure resistance of, and to easily form a blast groove for preventing explosion that exhibits a stable working pressure.

According to the third and fourth aspects of the invention, since the non-aqueous electrolyte battery is provided with a blast explosion prevention groove formed by laser light processing on the outer bottom surface of the battery container as a safety device, an abnormal environment is generated. When the internal pressure of the battery suddenly rises to a constant state due to the use of a battery, a battery explosion can be easily and reliably prevented. That is, the explosion-proof groove formed on the outer bottom surface of the battery container always shows a constant working pressure, and the explosion-proof groove causes the breaking action only when the inside of the battery rises to a constant pressure. Since it is involved in the required explosion prevention, the reliability and life of the non-aqueous electrolyte battery can be extended.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, FIG. 1 (a), (b) and FIG.
An example will be described with reference to FIG.

First, as a battery container, a stainless steel bottomed cylindrical body having a thickness of 0.3 mm and having an opening at one end which also serves as a negative electrode terminal is prepared, and a top surface shape conforming to the inner bottom surface shape of the bottomed cylindrical body is prepared. A columnar support having the above was also prepared. Then, the bottomed cylindrical body is fitted and arranged on the support base,
As shown in Fig. 1 (a) in plan view and in Fig. 1 (b) in cross section, the outer bottom surface of the bottomed cylindrical body is selectively irradiated with laser light and scanned to have a width of 0.3 mm and a depth of 0.24 mm. A rough explosion prevention groove of a certain degree was formed in an H shape in a plan view.

Here, the bottomed cylindrical body is formed by, for example, drawing, and the selective irradiation / scanning of laser light (laser light processing) is performed, for example, by a YAG laser device (KK. Toshiba product). , LAY-600D), input voltage 32
It is performed under the conditions of 0 V, pulse width 1.0 ms, and repetition rate 50 pps. In FIGS. 1 (a) and 1 (b), 1 is a bottomed cylindrical body (battery container), 1a is an outer bottom surface of the bottomed cylindrical body 2, 2 is an explosion explosion prevention groove, and 1b is an explosion explosion prevention groove. It is a thinned part (thickness of about 0.06 mm) due to the shape of 2.

By the above-mentioned processing operation, the explosion-proof grooves 2 formed respectively on the outer bottom surfaces 1a of the plurality of battery containers 1 are formed.
The cross-sectional shape (width, depth) was observed and evaluated. As a result, almost no variation was observed, and the explosion-proof groove 2 having a stable (uniform) cross-sectional shape was formed. That is, it was confirmed that the formed explosion-proof groove 2 exhibits a substantially uniform operating withstand voltage.

Next, an example in which a non-aqueous electrolyte battery is constructed by using the bottomed cylindrical body 1 with the blast explosion preventing groove 2 as a battery container which also serves as a negative electrode terminal will be described.

FIG. 2 is a cross-sectional view showing the structure of the main part of a non-aqueous electrolyte battery. Reference numeral 1 is stainless steel which also serves as a negative electrode terminal in which a non-aqueous electrolyte (organic electrolyte) battery power generating element 3 is incorporated. A battery container 4 made of steel with a groove 2 for preventing explosions, 4 is an insulator having an insertion hole 4a for a pipe-shaped positive electrode terminal 5 which is internally arranged above the battery power generating element 3, and 6 is an electrode having the positive electrode terminal 5 inserted therein. It is a stainless steel metal top (sealing body) that hermetically laser-seales the opening of the battery container 1 in which the battery power generating element 3 is installed. Here, the pipe-shaped positive electrode terminal 5 is
The pipe-shaped positive electrode terminal 5, which is used as a non-aqueous electrolyte injection port and is inserted through the metal top 6, is hermetically sealed by the glass sealing material 7 while ensuring electrical insulation with respect to the metal top 6. Sealed and fixed. Further, 8 is a lead wire for connecting the battery power generating element 3 and the positive electrode terminal 5, and 9 is a plug for sealing the pipe-shaped positive electrode terminal 5 by laser processing.

In the structure of the above non-aqueous electrolyte battery, the battery power generating element 3 is formed of a negative electrode (negative electrode constituent member), a positive electrode (positive electrode constituent member) and a non-aqueous electrolyte solution, and the negative electrode 3a is formed in a cylindrical shape. in metal lithium, which is crimped to the mounting and arranged on the inner wall surface of the battery container 1, the positive electrode 3c through the separator 3b ₁ made of glass fiber non-woven fabric is attached and arranged on the inside. The positive electrode 3c is a cylindrical porous carbon body 3c ₁ capable of impregnating and holding the non-aqueous electrolyte 3d, a cylindrical shape fitted and arranged inside the cylindrical porous carbon body 3c ₁ , It is composed of a current collector 3c ₂ made of a metal mesh.

More specifically, the cylindrical positive electrode 3c has carbon black and polytetrafluoroethylene in a weight ratio.
After adding 10% and further kneading by adding ethyl alcohol, press-molding into a tubular shape, insert the metal mesh current collector 3c ₂ into the hollow portion of the molded body, press-contact, and then
It is manufactured by drying and solidifying under a vacuum at a temperature of about 150 ° C. When mounting the battery container 1 inside, a glass fiber nonwoven fabric separator 3b ₂ is placed inside the bottom wall surface. Short circuit with the negative electrode side is prevented.

The non-aqueous electrolyte solution 3d is thionyl chloride (SOCl ₂ ) in which lithium aluminum tetrachloride (LiAlCl ₄ ) is dissolved at a rate of 1.2 mol / liter, for example.

On the other hand, for comparison, in the non-aqueous electrolyte battery having the above structure, a similar explosion-proof groove having a substantially H-shaped plan is formed on the outer bottom surface of the battery container by press working. Other than that, the non-aqueous electrolyte battery device was assembled and configured under the same conditions as above.

Comparative Example 1 A groove for preventing a burst explosion was formed by press working using a punch having a sharp tip.

Comparative Example 2 A groove for preventing a burst explosion was formed by press working using a punch having a tip of 0.1 to 0.2 mmR.

COMPARATIVE EXAMPLE 3 A punch having a tip of 0.1 to 0.2 mmR was used for press working to form a groove for preventing an explosion and then re-press working to flatten the protruding portion.

With respect to each of the non-aqueous electrolyte battery devices of the above-mentioned Examples and Comparative Examples 1 to 3, the operating pressure and the thin-walled part of the explosion-proof safety device were set.
The presence or absence of cracks in 1b, whether or not each non-aqueous electrolyte battery ruptured when it was thrown into a fire, the flatness of the outer bottom surface of the battery container, and the machinability of the explosion-proof groove ( Table 1 shows the results of evaluating the workability). In the numerical values in Table 1, the denominator is the number of tests, the numerator is the number of accidents, ⊚ indicates good, ∘ indicates slightly good, and x indicates poor.

Table 1 Compressive strength of thin-walled part (kg / cm ² ) Crack Rupture Flat work Thickness (mm) Average Max Min Min Existence Numerical Examples 0.06 68 87 53 0/100 0/20 ◎ ◎ Comparative Example 1 0.06 69 86 49 3/100 0/20 × × Comparative Example 2 0.06 81 118 63 0/100 3/20 × × Comparative Example 3 0.06 73 96 54 0/100 1/20 ○ × As shown in Table 1, the present invention In the case of a battery container with a groove that functions as an explosion-proof safety device with the processing method according to
Variations in pressure resistance were reduced, cracks did not occur in the thin portion, and stability and reliability were excellent. Further, even in a non-aqueous electrolyte battery, it exhibits good preventive property against explosion and significant improvement in safety and reliability is recognized.

On the other hand, in the case of the comparative example, if the variation in compressive strength is reduced, cracks occur in the piece or thin portion, or if there is no crack in the thin portion, variation in the piece or compressive strength or rupture occurs. Occurrence was observed and there was a problem in stability and reliability. The present invention is not limited to the above examples, and various modifications can be made without departing from the spirit of the invention. For example, the shape of the battery container may be a shape other than the cylindrical body, and it is also possible to adopt a configuration in which other substitutes than the above examples are selected as the battery constituent member.

[0037]

According to the inventions of claims 1 and 2, since a groove for preventing explosion is performed by laser light processing,
Not only the variations and problems of pressure strength due to work hardening are eliminated, but also the problems of press punch wear and damage are eliminated, and grooves that function as a highly reliable safety device, in other words, a burst explosion that exhibits a stable working pressure. Since the prevention groove can be formed easily with good reproducibility, it greatly contributes to the provision of a highly reliable explosion-proof battery.

According to the inventions of claims 3 and 4,
Since a highly reliable safety device (groove for preventing explosion) is provided, when the pressure inside the battery suddenly rises due to an abnormal environment, the battery explosion can be prevented easily and surely. That is, a highly safe non-aqueous electrolyte battery is provided.

[Brief description of the drawings]

FIG. 1 (a) is a plan view of the outer bottom surface of a battery container showing the structure of a storm explosion prevention groove of the embodiment, and (b) a sectional view of the battery container.

FIG. 2 is a cross-sectional view showing the configuration of a main part of a non-aqueous electrolyte battery of Example.

[Explanation of symbols]

1 …… Battery container (cylindrical body with a bottom) 1a …… Outside bottom surface of battery container 1b …… Thin-walled part (formation of groove for preventing explosion) 2 …… Groove for preventing explosion (safety device) 3 …… Battery generator element 3a …… Negative electrode 3b ₁ , 3b ₂ …… Separator 3c …… Positive electrode 3a ₁ …… Porous carbon body 3a ₂ …… Current collector 3d …… Non-aqueous electrolyte 4 …… Insulator 4a …… Insertion hole 5 Positive electrode terminal 6 Metal top (sealing body) 7 Glass sealing material 8 Lead wire 9 Plug body

Claims (4)

[Claims] 1. A method of grooving for preventing a burst explosion on the outer bottom surface of a metal battery container having a built-in battery power generation element, wherein the grooving is performed by laser light processing. Grooving method for preventing explosion. 2. The groove forming method for preventing explosion of a battery container according to claim 1, wherein the metal battery container is made of stainless steel. 3. A non-aqueous electrolyte battery in which a detonation prevention groove is formed on the outer bottom surface of a metal battery container containing a negative electrode constituent member, a positive electrode constituent member, and a battery power generating element having a non-aqueous electrolyte solution. A non-aqueous electrolyte battery, wherein the burst explosion prevention groove is formed by laser light processing. 4. The non-aqueous electrolyte battery according to claim 3, wherein the metal battery container is made of stainless steel.